similar case - http://www.overclock.net/t/640153/gtx-295-screwed-or-driver-problem - driver problem.
why are you dead set with it being the video card? whats your basis.
edit: my basis of why the driver may be a culprit is that its a "driver" and a "driver" drives the "GPU", hah! so if the "driver" is insane then it'd drive the "GPU" insane.
That is a completely different issue
1 those were in games not in windows the windows desktop never showed corruption
2 the system never locked up
This problem present in windows along with BSOD and FAILED memory tests
My basis?
I have done tect for 13+ years at this point
I am a current HP Lv2 escalation tech
I have worked for HP, AT&T, Dell and other places as well as do my own consulting business for local companies
If a tech sees a screen like that and doesn't immediately check the hard ware then they are not a knowledgeable tech.
In this case it was likely the bad system memory causing the video corruption
After the user swapped out to different memory the system ran fine except for 1 lockup which could have been caused by incorrect voltages etc
In the future you can use this
http://www.passmark.com/products/bit.htmNot just for burn in but testing
Set the 3d graphics test going and if it fails/artifacts then you know you have a graphics issue
If you are using on board you have to check the system memory
If using an add on card there really isn't much to check
You would only have insufficient power if the system wasn't built right along with lose cables
A failing power supply will present with other more annoying issues
And here have some links
Bad video card
http://hardforum.com/showthread.php?t=1216277Bad video card
http://www.geekyramblings.net/2008/09/18/bad-video-card/